1. Field of the Invention
The present invention relates to an improvement of a joining method for joining two ceramic bodies in a large size or in a complicated shape by heating electrically a butted portion to be jointed with, as main heat source, Joule heat caused by supplying electric current to the portion to be jointed, and more particularly to an improved joining method applicable for a method described below (a joining method to supply electric current to a ceramic body or a joining agent having an electric conductivity at a high temperature to complete the joining process).
2. Discussion of the Prior Art
A conventional joining method for joining electrically ceramic bodies is divided into the following four groups:
(A) A method which joins ceramic bodies by supplying electric current to the ceramic bodies or a joining agent having an electric conductivity at a high temperature. In this case, a joining agent is inserted at butted planes to be jointed between the ceramic bodies to form a butted portion and the portion is preheated with an auxiliary heating method by using a gas burner or a preheating means. After the ceramic bodies or the joining agent is in an electric conduction, the electric voltage is applied across at least two electrodes attached to the butted portion to be jointed to flow electric current through the electric conductive ceramic body or the joining agent at a high temperature. As a result, the plane to be jointed is heated with the Joule heat caused by the electric current flowing through the conductive ceramic body or the joining agent, and a reaction between the joining agent and the ceramic body is carried out to complete the joining.
(B) A method for joining ceramic bodies at least one of which has an electric conductivity at room temperature by permitting an electric current to flow through the electric conductive ceramic body in parallel to portion to be jointed.
A joining agent is inserted between the ceramic bodies at least one of which has an electric conductivity at room temperature. The ceramic body having an electric conductivity has two electrodes or an electrode in a belt form linked thereto at the vicinity of the butted portion and is supplied the electric current to the conductive ceramic body for heating the vicinity of the butted portion by Joule heat. As a result, the joining agent reacts with the ceramic bodies to join the butted planes of the ceramic bodies.
(C) A joining method in which an inserting member for heating having an electric conduction at room temperature is inserted between planes to be jointed of two ceramic bodies and is heated by an electric current flowing in parallel to the butted planes to be jointed.
(a) The inserting member for heating is composed of an electrically conductive ceramic body having the joining agents attached to the both surfaces thereof and is inserted into the butted planes to be jointed between ceramic bodies of an insulating property or of a high electrical resistance. The both terminal surfaces of the inserting member for heating are linked with at least two electrodes or an electrode in a belt form and are heated by an electric current flowing in parallel to the butted planes to be jointed. The Joule heat generated by the electric current heats the butted portion and executes the reaction between the joining agent and the ceramic bodies to complete the joining.
(b) The inserting member for heating is composed of an electric conductive ceramic base laminated by an insulating ceramic layer and is inserted into the butted planes to be jointed of ceramic bodies, at least one of which is in an electric conduction or between a metal body and a ceramic body in such an arrangement of facing the insulating ceramic layer to the electric conductive body to be jointed. The electric conductive ceramic of the inserting member for heating has at least two electrodes or a belt form electrode linked to the both terminals thereof and is heated by an electric current flowing in parallel to the butted planes to be jointed. The Joule heat generated by the electric current heats the butted portion and executes the reaction between the joining agent and planes of the ceramic bodies to complete the joining thereof.
(D) A method which joins bodies to be jointed having an electric conductivity at room temperature by permitting an electric current to flow in a direction crossing the butted planes to be jointed.
(a) A joining agent is inserted into butted planes to be jointed between ceramic bodies having an electric conductivity or between an electric conductive ceramic body and a metal body. The ceramic bodies having an electric conductivity or the electric conductive ceramic body and the metal body are provided with two electrodes, respectively and are heated an electric current flowing in a direction to cross the butted planes to be jointed. The Joule heat generated by the electric current heats the butted portion and executes the reaction between the joining agent and the planes of bodies to be jointed to complete the joining thereof.
(b) Butted portion to be jointed between electric conductive ceramic bodies or an electric conductive ceramic body and a metal body is formed by setting an inserting member for heating, has an electric conductivity less than that of the electric conductive ceramic body, there between with a joining agent. The two bodies to be jointed are connected with two electrodes, respectively and are heated by an electric current flowing in a direction to cross from one to another butted planes to be jointed. The Joule heat generated by the electric current heats the butted portion and executes the reaction between the joining agent and the bodies to be jointed to complete the joining thereof.